endian: Fix compilation error on NetBSD 7.1

[Bruno Haible]

On NetBSD 7.1.1, I'm seeing a compilation error:

gcc -std=gnu11 -DHAVE_CONFIG_H -DEXEEXT=\"\" -DEXEEXT=\"\" -I. -I../../gltests 
-I..  -DGNULIB_STRICT_CHECKING=1 -DIN_GNULIB_TESTS=1 -I. -I../../gltests -I.. 
-I../../gltests/.. -I../gllib -I../../gltests/../gllib -I/home/bruno/include 
-Wall  -Wno-error -g -O2 -MT test-htonl.o -MD -MP -MF $depbase.Tpo -c -o 
test-htonl.o ../../gltests/test-htonl.c &&\
mv -f $depbase.Tpo $depbase.Po
In file included from /usr/include/amd64/bswap.h:13:0,
                 from /usr/include/sys/endian.h:107,
                 from /usr/include/amd64/endian.h:3,
                 from /usr/include/sys/types.h:98,
                 from ../gllib/sys/types.h:46,
                 from ../gllib/sys/socket.h:51,
                 from ../gllib/arpa/inet.h:34,
                 from ../../gltests/test-htonl.c:22:
../gllib/endian.h:112:1: error: expected declaration specifiers or '...' before 
'(' token
 be16toh (uint16_t x)
 ^
../gllib/endian.h:112:1: error: expected ')' before '?' token
 be16toh (uint16_t x)
 ^
../gllib/endian.h:122:1: error: expected declaration specifiers or '...' before 
'(' token
 be32toh (uint32_t x)
 ^
../gllib/endian.h:122:1: error: expected ')' before '?' token
 be32toh (uint32_t x)
 ^
../gllib/endian.h:133:1: error: expected declaration specifiers or '...' before 
'(' token
 be64toh (uint64_t x)
 ^
../gllib/endian.h:133:1: error: expected ')' before '?' token
 be64toh (uint64_t x)
 ^
../gllib/endian.h:146:1: error: expected declaration specifiers or '...' before 
'(' token
 htobe16 (uint16_t x)
 ^
../gllib/endian.h:146:1: error: expected ')' before '?' token
 htobe16 (uint16_t x)
 ^
../gllib/endian.h:156:1: error: expected declaration specifiers or '...' before 
'(' token
 htobe32 (uint32_t x)
 ^
../gllib/endian.h:156:1: error: expected ')' before '?' token
 htobe32 (uint32_t x)
 ^
../gllib/endian.h:167:1: error: expected declaration specifiers or '...' before 
'(' token
 htobe64 (uint64_t x)
 ^
../gllib/endian.h:167:1: error: expected ')' before '?' token
 htobe64 (uint64_t x)
 ^
In file included from /usr/include/amd64/endian.h:3:0,
                 from /usr/include/sys/types.h:98,
                 from ../gllib/sys/types.h:46,
                 from ../gllib/sys/socket.h:51,
                 from ../gllib/arpa/inet.h:34,
                 from ../../gltests/test-htonl.c:22:
../gllib/endian.h:180:1: error: expected ')' before 'x'
 le16toh (uint16_t x)
 ^
../gllib/endian.h:190:1: error: expected ')' before 'x'
 le32toh (uint32_t x)
 ^
../gllib/endian.h:201:1: error: expected ')' before 'x'
 le64toh (uint64_t x)
 ^
../gllib/endian.h:214:1: error: expected ')' before 'x'
 htole16 (uint16_t x)
 ^
../gllib/endian.h:224:1: error: expected ')' before 'x'
 htole32 (uint32_t x)
 ^
../gllib/endian.h:235:1: error: expected ')' before 'x'
 htole64 (uint64_t x)
 ^
Makefile:27792: recipe for target 'test-htonl.o' failed
gmake[4]: *** [test-htonl.o] Error 1


The cause are system definitions of be16toh etc. as macros,
in the system's <sys/endian.h>.

This patch fixes it.


2024-12-28  Bruno Haible  <bruno@clisp.org>

        endian: Fix compilation error on NetBSD 7.1.
        * m4/endian_h.m4 (gl_ENDIAN_H): Test for <sys/endian.h>. Set
        HAVE_SYS_ENDIAN_H.
        * lib/endian.in.h: Test HAVE_SYS_ENDIAN_H as an alternative to
        HAVE_ENDIAN_H.
        * modules/endian (Makefile.am): Substitute HAVE_SYS_ENDIAN_H.

diff --git a/lib/endian.in.h b/lib/endian.in.h
index 156fe49fbd..09b5dfb42c 100644
--- a/lib/endian.in.h
+++ b/lib/endian.in.h
@@ -29,6 +29,10 @@
 /* The include_next requires a split double-inclusion guard.  */
 # @INCLUDE_NEXT@ @NEXT_ENDIAN_H@
 
+#elif @HAVE_SYS_ENDIAN_H@
+
+# include <sys/endian.h>
+
 #endif
 
 
@@ -69,7 +73,7 @@ _GL_INLINE_HEADER_BEGIN
 # define BYTE_ORDER LITTLE_ENDIAN
 #endif
 
-#if @HAVE_ENDIAN_H@
+#if @HAVE_ENDIAN_H@ || @HAVE_SYS_ENDIAN_H@
 
 /* Make sure we don't have any system definitions.  */
 # undef be16toh
diff --git a/m4/endian_h.m4 b/m4/endian_h.m4
index c205a44464..712c435fe8 100644
--- a/m4/endian_h.m4
+++ b/m4/endian_h.m4
@@ -1,5 +1,5 @@
 # endian_h.m4
-# serial 4
+# serial 5
 dnl Copyright 2024 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -80,6 +80,75 @@ AC_DEFUN_ONCE([gl_ENDIAN_H]
     HAVE_ENDIAN_H=0
   fi
 
+  AC_CHECK_HEADERS_ONCE([sys/endian.h])
+  if test $ac_cv_header_sys_endian_h = yes; then
+    HAVE_SYS_ENDIAN_H=1
+    dnl Check if sys/endian.h defines uint16_t, uint32_t, and uint64_t.
+    dnl Note: We don't use the result of this test for now.
+    AC_CACHE_CHECK([if sys/endian.h defines stdint types],
+      [gl_cv_header_sys_endian_h_stdint_types],
+      [AC_COMPILE_IFELSE(
+         [AC_LANG_PROGRAM(
+            [[#include <sys/endian.h>
+            ]],
+            [[uint16_t t1 = 0;
+              uint32_t t2 = 0;
+              uint64_t t3 = 0;
+              return !(t1 + t2 + t3);
+            ]])],
+      [gl_cv_header_sys_endian_h_stdint_types=yes],
+      [gl_cv_header_sys_endian_h_stdint_types=no])
+    ])
+    dnl Note: We don't use the result of this test for now.
+    AC_CACHE_CHECK([if sys/endian.h defines functions and macros],
+      [gl_cv_header_working_sys_endian_h],
+      [gl_cv_header_working_sys_endian_h=no
+       AC_COMPILE_IFELSE(
+         [AC_LANG_PROGRAM(
+[[
+#include <sys/endian.h>
+]],
+[[
+#if LITTLE_ENDIAN == BIG_ENDIAN
+# error "Endian macros not unique."
+#endif
+#if BYTE_ORDER != LITTLE_ENDIAN && BYTE_ORDER != BIG_ENDIAN
+# error "Byte order not defined."
+#endif
+
+/* Big endian to host.  */
+int value16_1 = be16toh (0.0);
+int value32_1 = be32toh (0.0);
+int value64_1 = be64toh (0.0);
+
+/* Host to big endian.  */
+int value16_2 = htobe16 (0.0);
+int value32_2 = htobe32 (0.0);
+int value64_2 = htobe64 (0.0);
+
+/* Little endian to host.  */
+int value16_3 = le16toh (0.0);
+int value32_3 = le32toh (0.0);
+int value64_3 = le64toh (0.0);
+
+/* Host to little endian.  */
+int value16_4 = htole16 (0.0);
+int value32_4 = htole32 (0.0);
+int value64_4 = htole64 (0.0);
+
+/* Make sure the variables get used.  */
+return !(value16_1 + value32_1 + value64_1
+         + value16_2 + value32_2 + value64_2
+         + value16_3 + value32_3 + value64_3
+         + value16_4 + value32_4 + value64_4);
+]])],
+         [gl_cv_header_working_sys_endian_h=yes],
+         [gl_cv_header_working_sys_endian_h=no])
+      ])
+  else
+    HAVE_SYS_ENDIAN_H=0
+  fi
+
   dnl Check if endian.h should be generated.
   if test "$gl_cv_header_endian_h_stdint_types" = yes \
      && test "$gl_cv_header_working_endian_h" = yes; then
@@ -100,5 +169,6 @@ AC_DEFUN_ONCE([gl_ENDIAN_H]
   fi
 
   AC_SUBST([HAVE_ENDIAN_H])
+  AC_SUBST([HAVE_SYS_ENDIAN_H])
   AC_SUBST([ENDIAN_H_JUST_MISSING_STDINT])
 ])
diff --git a/modules/endian b/modules/endian
index c4cef9dc90..676d5b6064 100644
--- a/modules/endian
+++ b/modules/endian
@@ -33,6 +33,7 @@ endian.h: endian.in.h $(top_builddir)/config.status
              -e 's|@''PRAGMA_COLUMNS''@|@PRAGMA_COLUMNS@|g' \
              -e 's|@''HAVE_ENDIAN_H''@|$(HAVE_ENDIAN_H)|g' \
              -e 's|@''NEXT_ENDIAN_H''@|$(NEXT_ENDIAN_H)|g' \
+             -e 's|@''HAVE_SYS_ENDIAN_H''@|$(HAVE_SYS_ENDIAN_H)|g' \
              -e 
's|@''ENDIAN_H_JUST_MISSING_STDINT''@|$(ENDIAN_H_JUST_MISSING_STDINT)|g' \
        $(srcdir)/endian.in.h > $@-t
        $(AM_V_at)mv $@-t $@